First your log file is labeled incorrectly.
restorecon /var/log/vgetty.log.*
What is it trying to do with /var/spool? Does it have a file it keeps there?
I will add the ability to search /var/spool (It should be there anyways.)
Can you do a setenforce 0
and then grab all of the avc messages?

restorecon doesn't do anything as vgetty is not in the targeted regexp file,
from what I can tell; only mgetty.log.* is in there.
#ll -Z /var/log/vgetty.log.ttyS0
-rw-r--r-- root root system_u:object_r:var_log_t /var/log/vgetty.log.ttyS0
#restorecon /var/log/vgetty.log.*
#ll -Z /var/log/vgetty.log.ttyS0
-rw-r--r-- root root system_u:object_r:var_log_t /var/log/vgetty.log.ttyS0
/var/spool/voice is where the playback message, as well as the recorded messages go.
Also, I have a script that vgetty calls when faxes are received that then places
converted faxes into an NFS mount. Same with voice messages. I take it I'll
have to modify my scripts to use only those directories which are explicitly
allowed by selinux, like /var/spool/voice? Or are the child processes (my
scripts) of vgetty exempt from selinux policies? (Having a script to handle new
voicemail & faxes is standard mgetty/vgetty procedure, so I'm not doing anything
weird here.)